lattice structure
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Intermediate filaments (IFs) are essential constituents of the metazoan cytoskeleton. A vast family of cytoplasmic IF proteins are capable of self-assembly from soluble tetrameric species into typical 10-12 nm wide filaments. The primary structure of these proteins includes the signature central 'rod' domain of ~ 300 residues which forms a dimeric α-helical coiled coil composed of three segments (coil1A, coil1B and coil2) interconnected by non-helical, flexible linkers (L1 and L12). The rod is flanked by flexible terminal head and tail domains. At present, the molecular architecture of mature IFs is only poorly known, limiting our capacity to rationalize the effect of numerous disease-related mutations found in IF proteins. Here we addressed the molecular structure of soluble vimentin tetramers which are formed by two antiparallel, staggered dimers with coil1B domains aligned (A11 tetramers). By examining a series of progressive truncations, we show that the presence of the coil1A domain is essential for the tetramer formation. In addition, we employed a novel chemical cross-linking pipeline including isotope labelling to identify intra- and interdimeric cross-links within the tetramer. We conclude that the tetramer is synergistically stabilized by the interactions of the aligned coil1B domains, the interactions between coil1A and the N-terminal portion of coil2, and the electrostatic attraction between the oppositely charged head and rod domains. Our cross-linking data indicate that, starting with a straight A11 tetramer, flexibility of linkers L1 and L12 enables 'backfolding' of both the coil1A and coil2 domains onto the tetrameric core formed by the coil1B domains. Through additional small-angle X-ray scattering experiments we show that the elongated A11 tetramers dominate in low ionic strength solutions, while there is also a significant structural flexibility especially in the terminal domains.
AIMS: Catheter ablation is an effective treatment method for recurrent ventricular tachycardias (VTs). However, at least in part, procedural and clinical outcomes are limited by challenges in generating an adequate lesion size in the ventricular myocardium. We investigated procedural and clinical outcomes of VT ablation using a novel 'large-footprint' catheter that allows the creation of larger lesions either by radiofrequency (RF) or by pulsed field (PF) energy. METHODS AND RESULTS: In prospectively collected case series, we describe our initial experience with VT ablation using a lattice-tip, dual-energy catheter (Sphere-9, Medtronic), and a compatible proprietary electroanatomical mapping system (Affera, Medtronic). The study population consisted of 18 patients (aged 55 ± 15 years, one woman, structural heart disease: 94%, ischaemic heart disease: 56%, left ventricular ejection fraction: 34 ± 10%, electrical storm: 22%) with recurrent sustained VTs and ≥1 previously failed endocardial RF ablation with conventional irrigated-tip catheter in 66% of patients. On average, 12 ± 7 RF and 8 ± 9 PF applications were delivered per patient. In three-fourths of patients undergoing percutaneous epicardial ablation, spasms in coronary angiography were observed after PF applications. All resolved after intracoronary administration of nitrates. No acute phrenic nerve palsy was noted. One patient suffered from a stroke that resolved without sequelae. Post-ablation non-inducibility of VT was achieved in 89% of patients. Ventricular-arrhythmia-free survival at three months was 78%. CONCLUSION: VT ablation using a dual-energy lattice-tip catheter and a novel electroanatomical mapping system is feasible. It allows rapid mapping and effective substrate modification with good outcomes during short-term follow-up.
- MeSH
- akční potenciály MeSH
- časové faktory MeSH
- design vybavení MeSH
- doba přežití bez progrese choroby MeSH
- dospělí MeSH
- elektrofyziologické techniky kardiologické * MeSH
- katetrizační ablace * metody přístrojové vybavení škodlivé účinky MeSH
- komorová tachykardie * chirurgie patofyziologie diagnóza MeSH
- lidé středního věku MeSH
- lidé MeSH
- prospektivní studie MeSH
- recidiva MeSH
- senioři MeSH
- srdeční katétry * MeSH
- studie proveditelnosti * MeSH
- výsledek terapie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Background: Aurora kinases are a recently discovered family of kinases (A, B & C) consisting of highly conservedserine\threonine protein kinases found to be involved in multiple mitotic events: regulation of spindle assembly checkpointpathway, function of centrosomes and cytoskeleton, and cytokinesis. Aberrant expression of Aurora kinases maylead to cancer. For this reason the Aurora kinases are potential targets in the treatment of cancer. In this review wediscuss the biology of these kinases: structure, function, regulation and association with cancer.Methods and Results: A literature search.Conclusion: Many of the multiple functions of mitosis are mediated by the Aurora kinases. Their aberrant expressioncan lead to the deregulation of cell division and cancer. For this reason, the Aurora kinases are currently one ofthe most interesting targets for cancer therapy. Some Aurora kinase inhibitors in the clinic have proven eff ectively ona wide range of tumor types. The clinical data are very encouraging and promising for development of novel class ofstructurally diff erent Aurora kinase inhibitors. Hopefully the Aurora kinases will be potentially useful in drug targetedcancer treatment.
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- aparát dělícího vřeténka genetika imunologie MeSH
- buněčný cyklus genetika imunologie MeSH
- cytokineze genetika imunologie MeSH
- cytoskelet genetika imunologie MeSH
- imunohistochemie metody využití MeSH
- lidé MeSH
- medicína založená na důkazech MeSH
- mikrozomy imunologie MeSH
- nádory etiologie genetika imunologie MeSH
- onkogeny genetika imunologie MeSH
- protein-serin-threoninkinasy genetika imunologie klasifikace MeSH
- protinádorové látky MeSH
- regulace genové exprese u nádorů genetika imunologie MeSH
- segregace chromozomů genetika imunologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
Invadopodia and podosomes have been intensively studied because of their involvement in the degradation of extracellular matrix. As both structures have been studied mostly on thin matrices, their commonly reported shapes and characteristics may differ from those in vivo. To assess the morphology of invadopodia in a complex 3D environment, we observed invadopodial formation in cells grown on a dense matrix based on cell-free dermis. We have found that invadopodia differ in morphology when cells grown on the dermis-based matrix and thin substrates are compared. The cells grown on the dermis-based matrix display invadopodia which are formed by a thick protruding base rich in F-actin, phospho-paxillin, phospho-cortactin and phosphotyrosine signal, from which numerous thin filaments protrude into the matrix. The protruding filaments are composed of an F-actin core and are free of phospho-paxillin and phospho-cortactin but capped by phosphotyrosine signal. Furthermore, we found that a matrix-degrading activity is localized to the base of invadopodia and not along the matrix-penetrating protrusions. Our description of invadopodial structures on a dermis-based matrix should greatly aid the development of new criteria for the identification of invadopodia in vivo, and opens up the possibility of studying the invadopodia-related signaling in a more physiological environment.
- MeSH
- aktiny metabolismus MeSH
- buněčné kultury MeSH
- buněčné výběžky metabolismus ultrastruktura MeSH
- cytoskelet metabolismus MeSH
- elektronová mikroskopie MeSH
- experimentální sarkom metabolismus ultrastruktura MeSH
- extracelulární matrix metabolismus fyziologie ultrastruktura MeSH
- fluorescenční protilátková technika MeSH
- kortaktin metabolismus MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- prasata MeSH
- signální transdukce MeSH
- zobrazování trojrozměrné MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The cortical microtubules, and to some extent also the actin meshwork, play a central role in the shaping of plant cells. Transgenic plants expressing fluorescent protein markers specifically tagging the two main cytoskeletal systems are available, allowing noninvasive in vivo studies. Advanced microscopy techniques, in particular confocal laser scanning microscopy (CLSM) and variable angle epifluorescence microscopy (VAEM), can be nowadays used for imaging the cortical cytoskeleton of living cells with unprecedented spatial and temporal resolution. With the aid of suitable computing techniques, quantitative information can be extracted from microscopic images and video sequences, providing insight into both architecture and dynamics of the cortical cytoskeleton.
OBJECTIVES: This study sought to evaluate the safety and acute performance of the lattice tip for the treatment of atrial flutter and fibrillation (AF). BACKGROUND: A novel catheter using an expandable lattice structure with a wide thermal footprint incorporating multiple surface thermocouples/mini-electrodes has been designed for high-resolution mapping and high-current, temperature-controlled radiofrequency ablation (RFA). METHODS: Patients with typical right atrial flutter or AF were prospectively enrolled in a single-arm study at 3 centers. Patients with atrial flutter underwent cavotricuspid isthmus (CTI) ablation. Patients with paroxysmal AF underwent pulmonary vein isolation (PVI) and CTI if desired, and for patients with persistent AF, mitral isthmus and left atrial roof lines were also permitted. Mapping was performed with the lattice (Sphere-9) catheter and a novel compatible electroanatomic mapping system (Prism-1). RFA was performed in a point-by-point fashion (Tmax, 73°C to 80°C; range 2 to 7 s). Patients were followed for 3 months. RESULTS: A total of 71 patients underwent ablation: 65 PVI (38% with persistent AF) and 22 mitral isthmus, 24 roof, and 48 CTI lines. PVI was achieved in 64 of 65 (98.5%) by using the lattice alone and required a mean of 2.7 ± 0.70 RFA min. Mitral block was achieved in 100% by using 11.5 ± 10.7 applications and 1.0 ± 0.92 RFA min; only 1 patient required adjunctive epicardial coronary sinus ablation. Roof line and CTI block were achieved in 95.8% and 100% of patients, using 4.9 ± 1.9 and 5.9 ± 3.1 applications for 0.4 ± 0.16 and 0.5 ± 0.24 RFA min, respectively. At 3 months, there were no deaths, strokes, tamponade, or atrioesophageal fistula. CONCLUSIONS: This first-in-human study demonstrated clinical feasibility and safety for rapid high-current, temperature-controlled point-by-point PVI and linear ablation.
- MeSH
- fibrilace síní * chirurgie MeSH
- katetrizační ablace * MeSH
- katétry MeSH
- lidé MeSH
- teplota MeSH
- venae pulmonales * chirurgie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Retroviruses assemble and bud from infected cells in an immature form and require proteolytic maturation for infectivity. The CA (capsid) domains of the Gag polyproteins assemble a protein lattice as a truncated sphere in the immature virion. Proteolytic cleavage of Gag induces dramatic structural rearrangements; a subset of cleaved CA subsequently assembles into the mature core, whose architecture varies among retroviruses. Murine leukemia virus (MLV) is the prototypical γ-retrovirus and serves as the basis of retroviral vectors, but the structure of the MLV CA layer is unknown. Here we have combined X-ray crystallography with cryoelectron tomography to determine the structures of immature and mature MLV CA layers within authentic viral particles. This reveals the structural changes associated with maturation, and, by comparison with HIV-1, uncovers conserved and variable features. In contrast to HIV-1, most MLV CA is used for assembly of the mature core, which adopts variable, multilayered morphologies and does not form a closed structure. Unlike in HIV-1, there is similarity between protein-protein interfaces in the immature MLV CA layer and those in the mature CA layer, and structural maturation of MLV could be achieved through domain rotations that largely maintain hexameric interactions. Nevertheless, the dramatic architectural change on maturation indicates that extensive disassembly and reassembly are required for mature core growth. The core morphology suggests that wrapping of the genome in CA sheets may be sufficient to protect the MLV ribonucleoprotein during cell entry.
- MeSH
- elektronová kryomikroskopie MeSH
- genové produkty gag chemie genetika ultrastruktura MeSH
- HEK293 buňky MeSH
- HIV-1 chemie genetika ultrastruktura MeSH
- kapsida chemie ultrastruktura MeSH
- krystalografie rentgenová MeSH
- kvarterní struktura proteinů MeSH
- lidé MeSH
- molekulární modely MeSH
- myši MeSH
- proteinové domény MeSH
- sekvence aminokyselin MeSH
- sekvenční homologie aminokyselin MeSH
- tomografie elektronová MeSH
- virion chemie genetika ultrastruktura MeSH
- virové plášťové proteiny chemie genetika ultrastruktura MeSH
- virus myší leukemie chemie genetika ultrastruktura MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Intramural MeSH
- srovnávací studie MeSH
